Manufacturing method of bamboo chip and manufacturing method bamboo fiber using the bamboo chip

ABSTRACT

There are provided a method for manufacturing a bamboo chip used to manufacture a natural fiber and a method for manufacturing a natural fiber using the bamboo chip. The method for manufacturing a bamboo chip includes steps of obtaining a soluble pulp from a bamboo chip; and manufacturing a rayon stable fiber from the soluble pulp using a viscose process as known in the prior art; and directly extracting only alpha-cellulose, in the form of fiber, from the bamboo chip by treating the bulky bamboo chip prepared in the present invention at a certain condition without undergoing a complicated process using raw materials for fiber articles as the rayon stable fiber. The alpha-cellulose in the form of fiber according to the present invention may be useful to apply to a variety of fields such as fibers, nonwoven fabrics and other sanitary articles, etc.

TECHNICAL FIELD

The present invention relates to a method for manufacturing a bamboochip used to manufacture a natural fiber and a method for manufacturinga bamboo fiber using the bamboo chip, and more particularly to a methodfor manufacturing a bamboo chip including steps of obtaining a solublepulp from a bamboo chip; and manufacturing a rayon stable fiber from thesoluble pulp using a viscose process as known in the prior art; anddirectly extracting only alpha-cellulose, in the form of fiber, from thebamboo chip by treating the bulky bamboo chip prepared in the presentinvention at a certain condition without undergoing a complicatedprocess using raw materials for fiber articles as the rayon stablefiber, wherein the alpha-cellulose in the form of fiber according to thepresent invention may be useful to apply to a variety of fields such asfibers, nonwoven fabrics and other sanitary articles, etc.

BACKGROUND ART

Generally, a cotton fiber is mainly obtained as natural cellulose fiberfrom cotton plants, but the cultivation of the cotton plants hasdecreased due to a variety of reasons such as environmental changes.Therefore, there has been an urgent need for novel natural cellulosefibers.

Accordingly, there have been attempts to obtain natural fiber materialsfrom bamboo, hemp, rice straw, corn stalk and the like in addition tothe natural cellulose obtained from the cotton plant. Among them, therehas been the most active attempt using a bamboo, but the studies usingbamboo stems have been mainly attempted and a study as fiber materialsis unsatisfactory until now.

Meanwhile, bamboo mainly grows and cultivates in Southeast Asiannations, and may be used as natural resources since the bamboo growsvery rapidly for a short period.

A process of manufacturing fiber materials from a bamboo, as known inthe art, will be described schematically.

First, a bamboo is harvested, bamboo leaves and stems are removed fromthe bamboo to obtain a cylindrical bamboo, and the cylindrical bamboo isthen cut to obtain a flat fragmental chip.

The flat fragmental chip has an approximately size with a width of 20 to30 mm, a length of 30 to 40 mm and thickness of 2 to 4 mm, as shown inFIG. 4, and includes a hard bark region, an inner bark and a jointregion. In this case, a soluble pulp may be prepared by treating thefragmental chip 1 with chemical agents under a various conditions.

As a result, a large amount of the chemical agents are increasingly usedto penetrate the chemical agents into the hard fragmental chip I in theabove-mentioned chemical treatment process, and therefore the treatmentprocess may be uneconomic due to the increase in the treatmenttemperature and time.

Also, even when the bamboo chip 1 is treated under the condition asdescribed above, the content of alpha-cellulose, which is required forfibrosis, is low due to the insufficient delignification and the lowefficiency to remove unnecessary components such as hemicellulose, andtherefore it is difficult to manufacture a good soluble pulp.

Furthermore, when the above-mentioned technique is used herein, a yieldof a soluble pulp is very low with a level of 30 to 37%, based on thetotal amount of the bamboo chip, and thus this process is not efficient.

In addition, a soluble pulp is gelated when the unnecessary componentssuch as lignin and hemicellulose, which act as obstacles to fibrosis, isremoved insufficiently, and then spun through a spinning process toobtain a filament yarn, or the soluble pulp is cut in a constant lengthto manufacture a stable fiber. However, the soluble pulp is increasinglycut finely since the components acting as obstacles to fibrosis arepresent in a large amount, and physical properties of fiber, such asstrength, uniformity and productivity, may be deteriorated, which leadsto the poor articles.

In particular, it is more difficult to manufacture a filament yarn as along fiber using the poor soluble pulp as described above.

In addition to the above-mentioned problems, large base facilities suchas chemical treatment facilities, spinning facilities, energy supplyfacilities and waste-water purifying facilities are required in afibrosis process using the soluble pulp, but some of the nations in theworld inhibit the operations of the base facilities since waste waterand environmental pollutions are seriously caused in the operations ofthe base facilities.

Therefore, there is an urgent demand for a method capable of solving theobstacles to fibrosis industries of bamboo that may grow in a largescale and be used as natural resources due to the rapid growth rate, aswell as having a more excellent antimicrobial activity than cotton fiberand excellent feeling sense, and therefore the above obstacles remainsto be solved.

DISCLOSURE OF INVENTION TECHNICAL PROBLEM

Accordingly, the present invention is designed to solve the aboveproblems, and therefore it is an object of the present invention toprovide a method for manufacturing a bamboo chip, wherein bamboo fibersmay be easily prepared through the simplified fibrosis process (adissolution process is omitted) by extracting alpha-cellulose from abamboo and manufacturing the alpha-cellulose into fibers, the method isenvironment-friendly, the facility investment and maintenance costs arehigh, and it is possible to mass-produce good bamboo fiber materialswith the low cost.

Technical Solution

In order to accomplish the above object, one embodiment of the presentinvention provides a method for manufacturing a bamboo chip used tomanufacture a natural fiber, the method including steps of obtaining acylindrical bamboo 10 by removing leaves and twigs from harvestedbamboo; obtaining a bamboo 12 having only bamboo stems by cutting andremoving bamboo joints 11 from the cylindrical bamboo 10; and tearingthe bamboo 12 into pieces in a longitudinal direction so as to givebulkiness by pressing the bamboo 12 with a pressure roller and a convexroller to crush the bamboo 12 in a longitudinal direction.

In order to accomplish the above object, another embodiment of thepresent invention provides a method for manufacturing a natural fiberusing a bamboo chip, the method including steps of adding the bamboochip 20 prepared in the method as defined in claim 1 and water in asolution ratio of 1:2.5 to 3.5 to a cooking container, heating thebamboo chip 20 at 160 to 180° C. for 100 to 180 minutes, and dischargingsteam and prehydrolyzing the bamboo chip 20 under a reduced pressure;washing the prehydrolyzed bamboo chip 20; adding 16 to 26% by weight ofcaustic soda (NaOH) (in a solution ratio of 1:2.5 to 3.5) and 0.1 to1.0% by weight of anthraquinone to a cooking container based on thetotal weight of the bamboo chip, and heating the mixture of the washedbamboo chip 20 at 130 to 150° C. for 60 to 120 minutes, heating themixture at 155 to 175° C. for 60 to 120 minutes once more, anddischarging steam at a reduced pressure; and washing the cooked bamboochip.

Also, additional processes includes steps of arranging and cutting theobtained bamboo fiber (alpha-cellulose fiber) into pieces having aconstant length, undergoing a reeling process and a concentrationprocess, bleaching the fibers several times, acid-treating the bleachedfibers, washing the fibers, and concentrating, pressing, drying andpackaging the washed fibers.

ADVANTAGEOUS EFFECTS

As described above, the method for manufacturing a bamboo fiber from abamboo according to the present invention may be useful to easilydissolve and remove impurities except for hemicellulose oralpha-cellulose such as lignin and pentoic acid that are unnecessary inthe fibrosis process using a bamboo chip manufactured from a cylindricalbamboo in which bamboo joints are removed from a bamboo since chemicalagents are easily penetrated into the bamboo chip in a prehydrolysis andcooking process by pressing the bamboo with a pressure roller or aconvex roller to crush the bamboo and tearing the bamboo into pieceswith scratches in a longitudinal direction so as to give rich bulkinessto the bamboo chip. Also, the manufacturing according to the presentinvention may be useful to mass-produce good and environment-friendlybamboo fibers without any investment of expensive facilities since abamboo fiber may be directly extracted from the above-mentioned bamboochip in the prehydrolysis and cooking process, and the bamboo fiber maybe then spun to produce a yarn, or used for various fiber articles suchas nonwoven fabrics, sanitary articles, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of preferredembodiments of the present invention will be more fully described in thefollowing detailed description, taken accompanying drawings. In thedrawings:

FIG. 1 is a configuration view showing a cylindrical bamboo used in thepresent invention,

FIG. 2 is a cross-sectional view showing a joint-free bamboo as shown inFIG. 1,

FIG. 3 is a cross-sectional view showing a bamboo chip having bulkinessthrough the pressing of the bamboo as shown in FIG. 2, and

FIG. 4 is a diagram showing a rectangular fragmental chip used in theconvention method for manufacturing a bamboo fiber.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed in detail referring to the accompanying drawings. Prior to thedescription, it should be understood that the terms used in thespecification and appended claims should not be construed as limited togeneral and dictionary meanings, but interpreted based on the meaningsand concepts corresponding to technical aspects of the present inventionon the basis of the principle that the inventor is allowed to defineterms appropriately for the best explanation. Therefore, the descriptionproposed herein is just a preferable example for the purpose ofillustrations only, not intended to limit the scope of the invention, soit should be understood that other equivalents and modifications couldbe made thereto without departing from the spirit and scope of theinvention.

Step 1: Preparation of Materials

Well-grown bamboo is harvested, and branches and leaves are removed fromthe harvested bamboo to obtain a cylindrical bamboo 10. Then, thecylindrical bamboo 10 is cut, and a region of bamboo joint 11 is removedfrom the cylindrical bamboo 10 to obtain a bamboo 12 that does not havea joint 11 (see FIG. 2).

In this case, the length of the resulting bamboo 12 is varied accordingto the growth conditions and states of the harvested bamboo, but thebamboo 12 has a length of about 15 to 50 cm.

However, there is no particular limitation on the length of the cutbamboo 12, but the bamboo 12 obtained by cutting off the joint 11 of theharvested cylindrical bamboo 10 is generally used as it is. Therefore,the length of the bamboo is preferably selected depending on the use andpurpose of the resulting bamboo fiber.

Step 2: Manufacture of Bamboo Chip

This process is important for the bamboo fiber provided in the presentinvention. In this process, a bamboo chip 20 having bulkiness isobtained by pressing the bamboo 12 prepared in the Step 1 with apressure roller or a convex roller with protrusions to crush the bamboo12 and tearing the bamboo 12 into pieces with scratches in alongitudinal direction (see FIG. 3).

As shown in FIG. 3, the subsequent process is preferably effectivelycarried out by pressing the entire bamboo 12 to crush the entire part ofthe bamboo 12 while making scratches to the bamboo 12, and the bamboo 12is simultaneously torn in a longitudinal direction to give bulkiness.

Articles, which are manufactured under the conditions as described inthe Korean Patent Application No. 2006-99406 filed by the presentinventors, may be used herein without manufacturing a bamboo chip underthe conditions as described above in the present invention.

Referring to the context of the prior application filed by the presentinventors, a bamboo from which leaves and twigs are removed is pressedwith a plurality of convex rollers to tear the bamboo while crushing thebamboo in a longitudinal direction, thereby to give bulkiness to thebamboo, and the bamboo is cut into pieces having desired length using acutting machine. In the crushing and cutting processes, joints,thin-walled tissues and silicated cuticles of the bamboo, which areobstacles to a pulping process, are crushed and removed partially.

Step 3: Washing Process

This process is to remove foreign substances attached to the bamboo chipand cleanly wash impurities such as small fragments and dusts generatedin the process of manufacturing a bamboo chip at the same time.

Step 4: Prehydrolysis Process

This process is to maximize a yield of fibrous alpha-cellulose includedin the bamboo chip by dissolving hemicellulose and lignin in the bamboochip.

In order to treat the bamboo chip, the prepared bamboo chip and waterare added to a cooking container and treated at a hot temperature for asuitable period.

In this case, a mixing ratio of the added bamboo chip and water rangesfrom 1:2.5 to 3.5% by weight, and the bamboo chip is sufficientlyimmersed in water in the cooking container. The bamboo chip is treatedat a temperature of 160 to 180° C. for 100 to 180 minutes, a steam isdischarged into a reduced pressure, and the bamboo chip treated in thecooking container is transferred into a washing process.

When the bamboo chip 20 is added to the cooking container together withthe bamboo chip 20 and treated at high temperature and high pressure foran extended time as described above, hemicellulose and some of lignin inthe bamboo chip are structurally changed, dissociated and dissolved bythe heating.

At the same time, pentoic acid that is present at a large amount ofabout 20% is also removed from the bamboo.

Particularly, the bulkiness is given to the bamboo chip used in thepresent invention since the bamboo chip is crushed in a longitudinaldirection and simultaneously torn into pieces with scratches during thepressing process. Therefore, it is possible to easily dissolvehemicellulose or lignin and pentoic acid in the prehydrolysis.

Step 5: Washing Process

This process is to wash dissolved hemicellulose or partially dissolvedlignin and pentoic acid in the prehydrolysis process so as to facilitatea cooking process.

Step 6: Cooking Process

This process is to remove lignin, which is not dissolved in theprehydrolysis process, in the most effective manner, but to extract onlypure alpha-cellulose without any damage to the alpha-cellulose in thebamboo chip.

Therefore, a process using caustic soda (NaOH) and anthraquinone mayapply to this process to improve the strength and yield of thealpha-cellulose.

That is to say, the bamboo chip undergoing the prehydrolysis and washingprocesses is added to a cooking container together with a suitableamount of caustic soda and a small amount of anthraquinone, and thentreated at a high temperature to sufficiently dissolve lignin andpentoic acid that are not dissolved and removed in the prehydrolysisprocess. As a result, only the pure fibrous alpha-cellulose remains inthe cooking container.

In the above treatment conditions, the alkaline compound is added at aratio of 16 to 26%, based on the compound (NaOH) used in the bamboo chipundergoing the pre-hydrolysis process. In this case, a solution ratio ofthe medicinal fluid (water, caustic soda and anthraquinone) ranges fromabout 1:2.5 to 3.5, based on the bamboo chip.

Also, the added anthraquinone is used to facilitate the removal oflignin but prevent the dissolution of alpha-cellulose, and the ratio ofthe added anthraquinone ranges from about 0.1 to 1.0% by weight, basedon the total weight of the bamboo chip.

The caustic soda and the anthraquinone are added to a cooking containertogether with bamboo chip under the conditions as described above, andthen primarily treated at 130 to 150° C. for about 60 to 120 minutes andsecondarily at 155 to 175° C. for 60 to 120 minutes.

Only the fibrous alpha-cellulose remains in the cooking container sincethe lignin and pentoic acid that are not dissolved in the prehydrolysisprocess are sufficiently dissolved in the heat treatment process.

When the bamboo chip is completely cooked under the above-mentionedconditions, a steam is discharged into a reduced pressure, and thefibrous product including only alpha-cellulose is then harvested fromthe cooking container, followed by undergoing a washing process.

Step 7: Washing Process

This process is to selectively extract the fibrous alpha-cellulose, forexample a bamboo fiber, by washing the dissolved lignin and pentoic acidin the cooking process with water.

During the washing process (Step 7), a desired bamboo fiber according tothe present invention is actually obtained.

That is to say, a fibrous alpha-cellulose, that is, a bamboo fiber isextracted from the bamboo chip. Then, the bamboo fiber may be spun toobtain a thread, or used to obtain various articles such as non wovenfabrics and sanitary articles.

However, the subsequent process is required to obtain a good bamboofiber.

Step 8: Alignment and Length Adjustment

This process is to align the bamboo fiber extracted in the previousprocess and adjust any length of the bamboo fiber as the same time.

Step 9: Removal of Foreign Substances

This process is to remove other foreign substances such as sands in thebamboo fiber by centrifuging the bamboo fiber aligned with any oflengths.

The centrifugation is carried out in a centrifuge under conditionsincluding a concentration of 0.5 to 0.8% and a pressure of 2 kg/D, andtherefore it is possible to effectively remove the foreign substancesthat have a higher specific gravity than the bamboo fiber.

Step 10: Concentration Process

The foreign substance-free bamboo fiber prepared in the Step 9 isconcentrated into a density of 2 to 3.5%.

Step 11: Bleaching Process

This is a bleaching process to obtain a good bamboo fiber by removingpigments in the bamboo fiber to improve brightness.

The bamboo fiber is primarily bleached with chlorine. In this case, thebleaching condition is as follows: 3.0 to 3.5% by weight of the bamboofiber is treated in 60% of the total amount of used chlorine for achlorinating time of 40 to 60 minutes, and then washed several timeuntil the remaining chlorine is 0.20 g/l and pH of the bamboo fiber ispH<2.

The primarily chlorine-bleached chlorine bamboo fiber undergoes asecondary bleaching process.

In this case, the secondary bleaching condition is as follows: =5.0% byweight of the bamboo fiber is treated in 2.0 to 2.5% of an alkalinecompound (based on a dry fiber) at a temperature of 50 to 90° C. for 60to 90 minutes, and then washed until the remaining alkaline compound is=50 g/D.

The secondarily bleached bamboo fiber undergoes the third bleachingprocess.

The third bleaching condition is as follows: the secondarily bleachedbamboo fiber is treated in 40% of the total amount of a used chlorinesolution including =250 g/D of an alkaline compound at a temperature of38 to 45° C. for a chlorinating time of 120 to 240 minutes, and thenwashed several time until a desired brightness is =75%, a content ofalpha-cellulose fiber is =93% and the remaining alkaline compound is =50g/D.

The bleached bamboo fiber has an excellent brightness and a goodquality.

Step 12: Acid-Treatment Process

This process is to stably maintain the brightness of the bamboo fiberbleached in the bleaching process. In this case, the bleached bamboofiber is treated in 2.0 to 5.0% of used acid (HCl) (based on a dryfiver) at a room temperature for 40 to 60 minutes, and then washed untilthe remaining acid is =50 g/D.

Step 13: Concentration Process

The acid-treated bamboo fiber is concentrated to a density of 3.0 to3.5% using a concentrator.

Step 14: Pressing and Drying Process

The concentrated bamboo fiber is pressed using a pressure roller toremove more than 80% of water from the bamboo fiber, and thewater-remove bamboo fiber is dried into a dryness of about 8.5 to 10%using a hot-wind dryer.

Step 15: Packaging Process

The suitably dried bamboo fiber is pressed into a reduced volume andpacked with easy handling and transportation at the same time.Therefore, the manufacture of the bamboo chip according to the presentinvention and the bamboo fiber extracted from the bamboo chip arecompleted.

MODE FOR THE INVENTION

As described above, as a substitute natural fiber from a cotton plantwhose cultivation tends to decrease, a natural fiber having moreexcellent antimicrobial activity than the cotton fiber and a smoothfeeling sense is extracted from a bamboo for use. In this case, articleshaving excellent physical properties such as tensile strength, feelingsense and antimicrobial activity may be mass-produced by manufacturing abamboo chip so that the bamboo can be treated in the process ofextracting a bamboo fiber without using the complicated process,investing the expensive facilities and causing the environmentfriend-associated problems, thereby to directly extract a bamboo fiberfrom a bamboo in a simple process, followed by directly extracting abamboo fiber including only alpha-cellulose from the bamboo chip, whichis used later in a spinning process or for nonwoven fabrics. That is tosay, the use of the bamboo fiber in the spinning process or for thenonwoven fabrics means that a bamboo fiber is spun as it is, ormanufactured into a nonwoven fabric without undergoing a conventionalrayon viscose process (pulp dissolution-spinning-cutting processes).

For the present invention, the condition of the bamboo chip is veryimportant to directly extract a bamboo fiber including onlyalpha-cellulose from the bamboo.

That is to say, the bamboo chip used in the present invention is not aconventional hard and fragment-type bamboo chip, but it is easilymanufactured by crushing a joint-free cylindrical bamboo with a lengthof 15 to 40 cm while pressing the cylindrical bamboo in a pressing unit,and tearing the cylindrical bamboo into fine chips in a longitudinaldirection, thereby to give bulkiness, which makes it easy to removeforeign substances, which is unnecessary in the fibrosis, such ashemicellulose or lignin, and pentoic acid, which are included in thebamboo, during the prehydrolysis and cooking process.

In particular, the bamboo fiber according to the present invention maybe useful to obtain a good bamboo fiber using a simple manufacturingprocess of directly extracting a bamboo fiber from a bamboo chip throughthe prehydrolysis and cooking process, the bamboo chip being prepared bypressing a long bamboo whose joints are removed from a cylindricalbamboo to crush the bamboo and tearing the bamboo in a longitudinaldirection, unlike the conventional process of obtaining a soluble pulpfrom a fragment-type hard bamboo chip; gelating the soluble pulp;obtaining a stable fiber using a viscose process and using the stablefiber as a fiber article material.

Referring again to the conventional process of extracting a bamboofiber, the conventional process includes a four-step process including abamboo chip—a soluble pulp—a bamboo stable fiber in a viscose process—afiber article, but the process according to the present inventionincludes a three-step process including a bamboo chip—a bamboo fiber—afiber article (treads, nonwoven fabrics, sanitary articles). Therefore,the process according to the present invention is carried out in asimple manner since the articles are produced without manufacturing astable fiber using the viscose process.

In addition, a process for manufacturing a stable fiber using aconventional viscose process may be omitted in the present inventionsince a bamboo fiber is directly extracted from the bamboo chip, andtherefore it is possible to mass-produce a bamboo fiber with low expensewithout any of the environmental pollutions and the deterioration ofproductivity and quality that are caused by the huge investment andoperation of the facilities.

The results obtained by comparing the conventional method formanufacturing a bamboo fiber with the manufacturing method according tothe present invention are listed in the following Table 1.

TABLE 1 Conventional method Inventive method Bamboo chip shape Hard andrectangular Torn in a longitudinal direction with bulkiness Hard bark,inner Very rich Very low bark and joint Bulkiness Very hard but notbulky Bulkiness by scratches Cooking time Long Short Dose of agentsLarge Small Alpha-cellulose Highly damaged Rarely damaged Tensilestrength Weak Strong No. of Processes 4 Processes 3 Processes(a stablefiber process omitted) Manufacturing cost Expensive Cheap(about 37%) andother expenses Peeling High Low Antimicrobial Low High activity FeelingMediocre Very smooth Rarity Under production First developmentApplication Restricted Various

Abstract

The present invention has been described in detail. However, it shouldbe understood that the detailed description and specific examples, whileindicating preferred embodiments of the invention, are given by way ofillustration only, since various changes and modifications within thespirit and scope of the invention will become apparent to those skilledin the art from this detailed description.

1. A method for manufacturing a bamboo chip used to manufacture anatural fiber, the method comprising: obtaining a cylindrical bamboo 10by removing leaves and twigs from harvested bamboo; obtaining a bamboo12 having only bamboo stems by cutting and removing bamboo joints 11from the cylindrical bamboo 10; and tearing the bamboo 12 into pieces ina longitudinal direction so as to give bulkiness by pressing the bamboo12 with a pressure roller and a convex roller to crush the bamboo 12 ina longitudinal direction, wherein the joint 11-free bamboo 12 has alength of 15 to 50 cm.
 2. A method for manufacturing a natural fiberusing a bamboo chip, the method comprising: adding the bamboo chip 20prepared in the method as defined in claim 1 and water in a solutionratio of 1:2.5 to 3.5 to a cooking container, heating the bamboo chip 20at 160 to 180° C. for 100 to 180 minutes, and discharging steam andprehydrolyzing the bamboo chip 20 under a reduced pressure; washing theprehydrolyzed bamboo chip 20; adding 16 to 26% by weight of caustic soda(NaOH) (in a solution ratio of 1:2.5 to 3.5) and 0.1 to 1.0% by weightof anthraquinone to a cooking container based on the total weight of thebamboo chip, and heating the mixture of the washed bamboo chip 20 at 130to 150° C. for 60 to 120 minutes, heating the mixture at 155 to 175° C.for 60 to 120 minutes once more, and discharging steam at a reducedpressure; and washing the cooked bamboo chip.
 3. The method formanufacturing a natural fiber according to claim 2, further comprising astep of bleaching the washed bamboo chip so as to improve brightness ofa fiber after the step of washing the cooked bamboo chip.